Liquid fuel injection systems for internal combustion engines



June 23, 1959 W E, w NICOLLS 2,891,530

LIQUID FUEL. INJECTION SYSTEMS FOR INTERNAL COMBUSTION ENGINES Filed May 27, 1957 2 sheets-sheet 1V June 23, 1959 w. E. w. NlcoLLs 2,891,536

LIQUID FUEL INJECTION SYSTEMS FOR INTERNAL COMBUSTION ENGINES 'fifi United States Patent ()tiice 2,891,530 Patented June 23., v1959 LIQUID FUEL INJECTION SYSTEMS FOR COMTBUSTIONv ENGINES rWilfrid Edward .Walter Nicolls, Pinner, England, assignor to C.A.V. Limited, London, England Application May 27, 1.957, Serial No. 661,690

Claims priority, application Great' Britain May 30, 1956 6 Claims. (Cl. 12S-139) -and i-s adapted to effect its: discharge by the action of engine cylinder air compression pressure, and a valve operable by pressure of the fuel supplied-by the metering pump for controlling the dischargeof ythe injection pump.

The metering pump may-be'ofanyconvenient variabledelivery type which is supplied by a feed pump-and is adapted to be driven through a mechanical connection with a rotary part of the engine. This` pump Vmay be of the reciprocatory plunger type having aplurality of plungers corresponding Vto the-number yof ,cylinders in theengine. Alternatively it. may :beof vthe distributor type wherein a single pumpingmeansisadapted tosupply each cylinder of the enginein turn through .a 4rotary distributor.

In the accompanying drawing:

Figure l is a sectional side elevation ofa liquidfuel injection systemaccording to the. invention.

Figures 2 and 3 are similar viewsto Figure :1 illustrating respectively two further embodiments of theinvention.

In the example shown. in Figure l the metering pump comprises a plurality of reciprocatory plungers as 3, according to the number of` cylinders inthe engine. Each plunger is contained in a cylinder `4, thesuction strokes of the plunger being affected by a spring 5, and the delivery strokes by an engine-drivenrotary cam 6. acting through a slipper 7 carrying -a rollervS. The fuelis .supplied by a feed pump to thefinlet 9, andy from the inlet the fuel can enter the cylinderthrougha port 10. Discharge of the` fuel bythe plunger is effected through a non-return valve 11V loaded by a spring v12, the fuel being conveyed by a pipe 13 toV the injectionpump. Relief of pressure in the said pipe for the purpose hereinafter mentioned is effectedsbya second"valvefllloaded by a spring 15 and arranged between Pthe-said pipe and a return passage 16, which is controlled by the plunger. In each discharge stroke of the-plunger thefirst effect of the plunger-is to'close the-port'fl. For ivarying the amount of 'the Vdischarge the-instantlat whichthe port is closed is variable by a substantially V-shaped notch 17 in the plunger. The position of this notch relatively to the port is variable by rotation of the plunger, this being effected by a toothed rack 18 which is operable by a speed governor or manually, and which engages a toothed segment 19 on the plunger.

The injection pump comprises a cylinder 20, containing a plunger 21, which is actuated by a mechanism responsive to cylinder air pressure at or near the end of a compression stroke, an injection pump Ibeing provided for each of the engine cylinders. In the example illustrated, the discharge stroke of the injection pump bore being in communicationV with thepassage 34.

plunger is effected through a rocker lever 22 one-end of which acts. on. the plunger through a slipper 23, loaded by a spring 24, the other end of the leverl being connected by a rod 25 to a piston 26 in a cylinder 27 'communicating with the engine cylinder, the piston being loaded by a spring 29. The arrangement is such that the pressure in the engine cylinder when its piston 28 approaches the inner end of its stroke is .utilized for moving the plunger-actuating piston 26 against the action of the associated spring 29 for effecting the discharge stroke of the injection plunger, the return stroke of the actuating piston being effected by the spring.

For controlling a passage 30 between the cylinder of the injection pump and the injection nozzle 31'inthe engine, there is provided a piston valve 32 loadedby a spring 33 and contained in a cylindrical borefwhich is connected by a passage 34 to the pipe 13. On the valve is formed a circumferential groove 35 which when the valve is in its open position as shown interconnects adjacent parts `of the passa-ge 30. For limiting the extent of axial movement of the valve in one direction, the valve is provided at one end -With a flange 32a which, when Athe valve is. in its open position, is caused by the loading end of the bore containing this valve and the cylinder of the injection pump is provided a valve 36 loaded by a spring 37 through which the fuel supplied by the metering pump to the passage 34 can enter the injection pump.

The injection nozzle contains a Valve 33 which is loaded by a spring 39. This valve controls the outlet of the nozzle, and is raised olf its seating lby pressure of the fuel discharged from theinjection pump.

The arrangement is such that in eac'h delivery stroke of the metering pump, the first effect of the pressure of the discharged fuel is to move the piston Valve 32 against the action of Ithe spring 33 to its shut position on which it obstructs the passage 30. The fuel discharged bythe metering pump then passes through the valve 36 to the injection pump. During the following suction stroke of the metering pumpthe passage 16 is uncovered by the plunger 3 and the resulting fall of pressure inthe part of the system between lthe two pumps lallows the spring 33 acting on the piston valve 32 -to return it to: its open position, and in this movement of -the valve the fuel displaced thereby is returned to the metering pump inlet. The engine pressure then causes the plunger of the injection pump to discharge thel contents of this pump to the fuel injection nozzle. When the engine cylinder is opened to exhaust the piston 26 which acts on the injection pump plunger is returned to its initial position Vby its springin readiness for the next cycle of action.

.In the alternative varrangement of the invention shown in Figure 2, there is combined with the system, and-conveniently in `combination with the injection pump, an accumulator comprising a piston 40 .contained in'a cylindrical bore and loaded by a spring 41, one rend. of the In this arrangement the valve 32 initially occupies the shut position as shown in which it obstructs the passage 30. Further the metering pump is provided only with the above described discharge valve 11, loaded by a spring 12, the Valve 14 being not required.

When the system is in action, the first effect of the pressure of the fuel in each discharge from the metering pump is to move the valve 32 against the action of the spring 33 to its open position in which it allows the previously charged injection pump to discharge its content to the nozzle 31 under the action of engine pressure. Meanwhile the metering pump charges the accumulator.

3 After the injection pump has performed its duty and while the metering pump is drawing in a new charge, the accumulator discharges its content to thc injection pump.

In the further alternative arrangement shown in Figure 3, the injection pump and the injection nozzle are constructed as separate components, for enabling the invention to be used in conjunction with any suitable nozzle of standard form. The injection pump comprises a plunger 212 contained in a cylinder- 202 which is adapted to be accommodated in a cylinder 272. Within the cylinder 272 is contained a piston 262 which is loaded by a spring 292 and is movable against the action of the spring by the pressure in the engine cylinder, the piston being arranged to act directly on the plunger 212. Above the cylinder 202 is mounted a valve box 44 containing the piston valve 322 which is loaded by a spring 332. Liquid fuel is conveyed from the metering pump by a pipe 13 to the part of the bore in the valve box between one end of the valve 322 and the valve 362, and is supplied to the cylinder 202 through the valve 362. At the same time the incoming fuel moves the valve 322 to the position at which it isolates the cylinder 202 and passage 302 from the pipe 4S whereby the valve box is connected to the injection nozzle.

The arrangement is such that after the cylinder 202 has received its charge of fuel from the metering pump the valve 322 returns to the position shown under the action of the spring 332, and subsequently this charge is delivered to the nozzle by the action of the piston 262 on the plunger 212.

The injection nozzle may be of any convenient and suitable form. In the example illustrated it consists of a hollow body part 46 containing an outlet-controlling closure member 382 which is loaded by a spring 47 acting through a stem 48. In the part 46 is formed a passage 303 which conveys the fuel from the pipe 45 to the lower end of the closure member 382 the latter being moved upwardly by the pressure of the fuel acting in opposition to the spring 47 `for opening the discharge outlet of the nozzle.

The metering pump is similar to that already described with reference to Figure 1, the various pars being indicated by the same reference numerals as those eniployed in Figure 1.

By this invention the duty imposed on the metering pump is solely that of delivering measured quantities of fuel at relatively low p-ressure. The duty of discharging the fuel to the engine at high pressure is performed by the injection pump. Consequently the actuating means of the metering pump is not subjected to a heavy load, and is ltherefore not liable to be deranged by excessive wear or strain. Moreover the actuating means of the injection pump is of a simple and robust character which can readily be made to withstand the duty imposed on- 1t.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

l. A liquid fuel injection system for an internal combustion engine in which air is compressed preparatory to the injection thereinto of liquid fuel, comprising in combination a liquid fuel metering pump provided with actuating means operable by the engine, and with a fuel inlet and a fuel outlet, a liquid fuel injection pump also provided with a fuel inlet and a fuel outlet, fueltransfer means ."iterconnecting the fuel outlet of the metering pump an the fuel inlet of the injection pump so that the latter c.`"-.`be supplied with liquid fuel by the metering pump "rough the fuel-transfer means, pressure-responsive m1 ns operable by the engine air compression pressure for effecting discharge of the injection pump, and a Valve arranged to control the discharge of the injection pump, and :to be operated by the pressure of the fuel delivered by the metering pump.

2. A liquid fuel injection system for an internal combustion engine in which air is compressed preparatory to the injection thereinto of liquid fuel, comprising in combination a liquid fuel metering pump provided with actuating means operable by the engine, and with a yfuel inlet and a fuel outlet, a liquid fuel injection pump also provided With a fuel inlet and a fuel outlet, fuel-transfer means interconnecting the fuel outlet of the metering pump and the fuel inlet of the injection pump so that the latter can be supplied with liquid fuel by the metering pump through the fuel-transfer means, and pressureresponsive means operable by the engine air compression pressure for effecting discharge of the injection pump, the latter having in combination a plunger operable by the pressure-responsive means, a cylinder in which the plunger is slidable, and to which fuel from the metering pump Khas access through the fuel inlet of the injection pump, a springeloaded piston valve arranged to control discharge of fuel from the cylinder through the fuel outlet of the injection pump, and to be moved against its spring loading by the pressure of the fuel delivered by the metering pump, a passage forming the fuel inlet of the injection pump, and arranged to conduct fuel from the metering pump to one end of the piston valve, and a spring-loaded, non-return valve arranged ybetween the said passage and cylinder.

3. A system according to claim 2, in which the piston valve initially occupies an open position, and in which a fuel pressure relief valve controllable by the metering pump is arranged between the llatter and the fuel-transfer means.

4. A system according to claim 2, in which the piston valve initially occupies a closed position, and in which a fuel accumulator chargeable by the metering pump is arranged in communication with the fuel inlet of the injection pump.

5. A system according to claim 2, in which the pressure-responsive means comprises a spring-loaded piston movable against its spring loading by the engine air compression pressure, and arranged lto act directly on the plunger of the injection pump.

6. A system according to claim 2 and having a fuel injection nozzle in the form of a separate unit connected to the outlet of the injection pump.

References Cited in the tile of this patent UNITED STATES PATENTS 1,901,835 Thomas Mar. 14, 1933 2,313,264 Reggio Mar. 9, 1943 2,522,890 Peterson Sept. 19, 1950 

